Method for determining content of niobium in manganese-silicon alloy

Abstract

The application belongs to the technical field of analysis and detection, and particularly relates to a method for determining the content of niobium in manganese-silicon alloy. The steps are as follows: S1: sample preparation; S2: placing the crushed sample in a 100 mL polytetrafluoroethylene beaker, adding 1-5 mL dilute nitric acid, fully shaking, then adding 1-5 mL hydrofluoric acid dropwise until the sample is completely dissolved, adding 3-5 mL silicon standard solution, heating and boiling on a heating device for 2-3 min, taking off and cooling, then transferring to a 100 mL polyethylene volumetric flask, diluting to the scale with water, shaking, drying, filtering, and then measuring; S3: preparing a working curve; S4: determining and analyzing the spectral line intensity of the element by an inductively coupled plasma atomic emission spectrometer, taking the concentration of the analyzed element as the abscissa and the spectral line intensity as the ordinate, drawing a calibration curve, and determining the content of niobium in the sample. Compared with the prior art, the method is simpler, has low cost, and is fast in analysis.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing technology, specifically relating to a method for determining the niobium content in manganese-silicon alloys. Background Technology

[0002] Manganese-silicon alloys, used as deoxidizers, alloying agents, and metallurgical reducing agents in steelmaking, can promote the deoxidation reaction of silicon and improve the strength, hardness, and other properties of steel. They are widely used in the production of low-carbon steel, killed steel, and stainless steel. Niobium, an element in these alloys, directly enters the steel during the smelting process. The niobium content significantly enhances the performance of the steel, giving it good toughness and weldability while maintaining high strength. By rationally controlling the niobium content, the performance of the steel can be significantly improved, thereby meeting the market demand for high-performance steel.

[0003] Currently, there are no literature reports on the analysis of niobium content in manganese-silicon alloys. Only methods for determining niobium content in related fields such as steel, ferroniobium, niobium-phosphorus alloys, ferrosilicon, and niobium concentrate exist, including paper-based color separation gravimetric analysis, PAR spectrophotometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluorescence spectrometry, and direct-reading photoelectric spectrometry. Among these, ICP-AES is relatively simple and accurate; however, due to the special properties of niobium and its corresponding alloys, sample preparation is complex, requiring the addition of large amounts of acid. Furthermore, because niobium is highly hydrolyzable, after sample dissolution, perchloric acid is used to remove hydrofluoric acid before tartaric acid is added for complexation and stability. This method is quite complex and can easily introduce interference for low-content analyses. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for determining the niobium content in manganese-silicon alloys. After directly dissolving the sample in a nitric acid-hydrofluoric acid system, the sample is transferred to a silicon monophosphate standard solution and boiled at 120°C to remove silicon tetrafluoride and excess hydrofluoric acid. The niobium content is then directly detected using inductively coupled plasma atomic emission spectrometry (ICP-AES), thus solving the problem of directly determining niobium content without adding a complexing agent and significantly reducing the analytical process.

[0005] The technical solution adopted in this invention is a method for determining the niobium content in a manganese-silicon alloy, comprising the following steps: Step S1: Crush the manganese silicon alloy sample to be tested to a particle size of less than 0.125 mm to obtain the crushed sample; Step S2: Place the pulverized sample in a 100 mL polytetrafluoroethylene beaker, add 1-5 mL of dilute nitric acid, shake well, then add 1-5 mL of hydrofluoric acid until the sample is completely dissolved. Add 3-5 mL of silicon standard solution and heat on a heating device to boil for 2-3 minutes. Remove and cool, then transfer to a 100 mL polyethylene volumetric flask, dilute with water to the mark, shake well, filter dry, and then test. Step S3: Prepare the working curve; Step S4: Adjust the inductively coupled plasma atomic emission spectrometer to the optimal working conditions, measure the intensity of the spectral lines of the analyte using the inductively coupled plasma atomic emission spectrometer, plot the calibration curve with the concentration of the analyte as the abscissa and the spectral line intensity as the ordinate, and determine the niobium content in the sample.

[0006] Furthermore, in step S2, the amount of sample is 0.10–0.25 g, and the concentration of the silicon standard solution is 2 mg / mL.

[0007] Preferably, in step S2, 5 mL of dilute nitric acid, 2 mL of hydrofluoric acid, and 5 mL of silicon standard solution are added.

[0008] Further, step S3 specifically involves: weighing 6 portions of high-purity iron and placing them in 6 100mL tetrafluoroethylene beakers, wetting them with water, adding 5mL of dilute nitric acid, heating at 150°C to remove the yellow fumes, then adding 0.1mL of hydrofluoric acid, shaking thoroughly until the solution dissolves, removing and cooling, adding 5mL of silicon standard solution, transferring to a 100mL volumetric flask, then adding different volumes of standard stock solution or standard working solution, making up to volume, and shaking well.

[0009] Furthermore, in step S3, the sample weight of high-purity iron is 0.04 g to 0.1 g, and the content gradient of niobium standard solution is 0% to 0.5%.

[0010] Furthermore, in step S4, the optimal operating conditions for the inductively coupled plasma atomic emission spectrometer are: power 1150 kW, atomizer pressure 26 psi, pump speed 100 rpm, cleaning time 20 s, and integration time 5–20 s.

[0011] The beneficial effects of this invention are: (1) The present invention uses hydrofluoric acid to dissolve the sample, then uses silicon solution to complex the excess hydrofluoric acid, and then removes silicon tetrafluoride by heating and boiling. It does not require the use of a hydrofluoric acid resistant system and directly uses conventional injection system to determine the niobium content by ICP spectroscopy. By introducing silicon standard solution, the corrosion of conventional glass injection system by hydrofluoric acid is effectively eliminated, and the lengthy sulfuric acid fume step is omitted. At the same time, the addition of tartaric acid is avoided to reduce the strength of niobium. The method is fast, simple, low cost and fast analysis speed.

[0012] (2) The present invention can maintain the stability of niobium in solution by complexing it with hydrofluoric acid, making it less prone to hydrolysis and thus obtaining more accurate analytical results.

[0013] (3) The present invention uses silicon solution and excess hydrofluoric acid to generate silicon tetrafluoride and remove it by heating, which can greatly reduce the formation of salts in the solution and thus further improve the accuracy of analysis.

[0014] (4) Compared to existing methods that require the addition of tartaric acid to complex niobium-containing samples with hydrofluoric acid or the use of perchloric acid to remove hydrofluoric acid before ICP spectroscopy analysis, this invention offers a simpler treatment method. It eliminates the need for evaporation followed by salt dissolution and the addition of tartaric acid to complex niobium. This method boasts advantages such as a lower detection limit, higher sensitivity, simpler operation, simpler analytical conditions, and significantly shorter analysis time. Compared to existing inductively coupled plasma atomic emission spectrometry (ICP-AES) for determining niobium content, this invention offers advantages such as lower acid consumption, lower labor intensity, and shorter analysis time. Therefore, this invention has significant economic benefits and is simple and economical. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is the overall flowchart of the method of the present invention. Detailed Implementation

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0018] like Figure 1 As shown, the present invention provides a method for determining the niobium content in a manganese-silicon alloy, comprising the following steps: Step S1, Pre-analysis preparation: The manganese silicon alloy sample to be tested is crushed to a particle size of less than 0.125 mm to obtain the crushed sample; Step S2, Sample decomposition: Weigh 0.2000g ± 0.0002 of the pulverized sample and place it in a 100 mL polytetrafluoroethylene beaker. Add 1–5 mL of dilute nitric acid, shake well, and then add 1–5 mL of hydrofluoric acid until the sample is completely dissolved. Add 3–5 mL of 2 mg / mL silicon standard solution and heat on a heating device to boiling for 2–3 min. Remove from heat and cool. Then transfer to a 100 mL polyethylene volumetric flask, dilute with water to the mark, shake well, filter dry, and wait for testing. Step S3: Preparation of the working curve: Weigh six portions of 0.0800 g ± 0.0002 g high-purity iron and place them in six 100 mL polytetrafluoroethylene beakers respectively. Moisten with water, then add 5 mL of dilute nitric acid. Heat at 150°C until the yellow fumes are exhausted, then add 0.1 mL of hydrofluoric acid. Shake thoroughly until the solution dissolves. After cooling, add 5 mL of silicon standard solution and transfer to a 100 mL volumetric flask. Then add different volumes of standard stock solution or standard working solution, dilute to volume, and shake well. The mass concentrations of niobium in this standard solution series are 0, 0.010, 0.20, 1.0, 2.0, and 10 μg / mL.

[0019] Step S4, ICP determination: Adjust the inductively coupled plasma atomic emission spectrometer (ICP-AES) to optimal operating conditions. Select appropriate points according to the analytical element determination requirements. Measure the spectral line intensities of the analytical elements using ICP-AES. Plot a calibration curve with the analytical element concentration on the x-axis and the spectral line intensity on the y-axis. Based on the measured spectral line intensities, find the corresponding concentration values ​​on the calibration curve. Combined with the sample mass and dilution factor, calculate the actual niobium content in the manganese-silicon alloy. This method effectively eliminates the corrosion of conventional glass sample introduction systems by introducing a silicon standard solution, omits the lengthy sulfuric acid fume step, and avoids the reduction of niobium intensity by adding tartaric acid. This improves the accuracy and precision of the detection. The operation is simple and quick, suitable for rapid analysis of batch samples, and provides reliable technical support for the quality control of manganese-silicon alloys.

[0020] It should be further noted that the optimal operating conditions for the inductively coupled plasma atomic emission spectrometer are: power 1150W; nebulizer pressure 26psi; pump speed 100rpm; cleaning time 20s; integration time 5-20s.

[0021] The following examples provide further details.

[0022] Example 1: Step 1: Preparation before analysis: The manganese silicon alloy sample is crushed to a particle size of less than 0.125 mm.

[0023] Step 2: Sample decomposition Weigh 0.2000 g ± 0.0002 g of the pulverized sample and place it in a 100 mL polytetrafluoroethylene beaker. Add 5 mL of dilute nitric acid, shake well, and then add 2 mL of hydrofluoric acid until the sample is completely dissolved. Add 5 mL of 2 mg / mL silicon standard solution, and then heat on an electric furnace to boil for 2–3 min. Remove from heat and cool, transfer to a 100 mL polyethylene volumetric flask, dilute with water to the mark, shake well, filter dry, and then test.

[0024] Step 3: Setting up the working curve Six portions of 0.0800 g ± 0.0002 g high-purity iron were weighed and placed in six 100 mL polytetrafluoroethylene beakers. 15 mL of water was added, followed by 5 mL of dilute nitric acid. The mixture was heated at 150°C until the yellow fumes were exhausted. 0.1 mL of hydrofluoric acid was then added dropwise, and the mixture was shaken thoroughly until dissolved. After cooling, 5 mL of silicon standard solution was added, and the mixture was transferred to a 100 mL volumetric flask. Different volumes of standard stock solution or standard working solution were then added, and the mixture was brought to volume and shaken well. The niobium concentrations in this standard solution series were 0, 0.010, 0.20, 1.0, 2.0, and 10 μg / mL.

[0025] Step 4: ICP determination Adjust the inductively coupled plasma atomic emission spectrometer to its optimal operating conditions, select appropriate points according to the analytical element determination requirements, and measure the spectral intensity of each analytical element using the inductively coupled plasma atomic emission spectrometer. Plot a calibration curve with the analytical element concentration as the abscissa and the spectral intensity as the ordinate, and then measure the sample.

[0026] The accuracy of the analytical method was determined by the spiked recovery rate. First, the niobium content in sample 1, sample 2, and sample 3 was detected using the method of this embodiment. Then, a known standard substance was added, and the niobium content of the three spiked samples was determined using the method of this embodiment. The recovery rate was calculated to obtain the detection accuracy. The results are shown in Table 1.

[0027] Table 1: Results of Spiked Recovery Test ; As shown in Table 1, the recovery rate of the method of the present invention is 105% when the niobium content is 0.0025%; 95% when the niobium content is 0.019%; and 104% when the niobium content is 0.042%. Therefore, the accuracy of the method of the present invention in determining the niobium content in manganese-silicon alloys meets the analytical requirements.

[0028] Example 2: Step 1: Preparation before analysis: The manganese silicon alloy sample is crushed to a particle size of less than 0.125 mm.

[0029] Step 2: Sample decomposition Weigh 0.2000 g ± 0.0002 g of the pulverized sample and place it in a 100 mL polytetrafluoroethylene beaker. Add 1 mL of dilute nitric acid, shake well, and then add 5 mL of hydrofluoric acid until the sample is completely dissolved. Add 3 mL of 2 mg / mL silicon standard solution, and then heat on an electric furnace to boil for 2–3 min. Remove from heat and cool, transfer to a 100 mL polyethylene volumetric flask, dilute with water to the mark, shake well, filter dry, and then test.

[0030] Step 3: Setting up the working curve Six portions of 0.0800 g ± 0.0002 g high-purity iron were weighed and placed in six 100 mL polytetrafluoroethylene beakers respectively. The beakers were moistened with water, and then 5 mL of dilute nitric acid was added. The mixture was heated at 150°C until the yellow fumes were exhausted. 0.1 mL of hydrofluoric acid was then added dropwise, and the mixture was shaken thoroughly until dissolved. After cooling, 5 mL of silicon standard solution was added, and the mixture was transferred to a 100 mL volumetric flask. Then, different volumes of standard stock solution or standard working solution were added, and the mixture was brought to volume and shaken well. The mass concentrations of niobium in this series of standard solutions were 0, 0.010, 0.20, 1.0, 2.0, and 10 μg / mL.

[0031] Step 4: ICP determination Adjust the inductively coupled plasma atomic emission spectrometer to its optimal operating conditions. Based on the analytical element determination requirements, select appropriate points from the above points and measure the spectral intensity of each analytical element using the inductively coupled plasma atomic emission spectrometer. Plot a calibration curve with the analytical element concentration as the abscissa and the spectral intensity as the ordinate, and then measure the sample.

[0032] The method described in this example was used to determine the niobium content of three samples eleven times. The results are shown in Table 2.

[0033] Table 2: Results of eleven determinations of niobium content in manganese-silicon alloys ; As shown in Table 2, the precision of the method of the present invention is 4.5% when the niobium content is 0.0025%; 5.8% when the niobium content is 0.0025%; and 3.0% when the niobium content is 0.042%. This indicates that the precision of the method of the present invention can meet the analytical requirements.

[0034] Comparative Example 1: The difference from Example 1 is in step 2, sample decomposition: the sample is placed in a 100 mL polytetrafluoroethylene beaker, 5 mL of dilute nitric acid is added, and after thorough shaking, hydrofluoric acid is added dropwise until the sample is completely dissolved. Then, 2 mL of sulfuric acid is added until it fumes and is nearly dry. Water is added to dissolve the salts, and then 5 mL of tartaric acid is added. The mixture is heated on an electric furnace and boiled for 2-3 minutes. After cooling, it is transferred to a 100 mL polyethylene volumetric flask, diluted with water to the mark, and shaken well. After filtration, it is ready for testing.

[0035] The above method was used to measure two sample specimens, and the results are shown in Table 3.

[0036] Comparative Example 2: The difference from Example 1 is in step 2, sample decomposition: the sample is placed in a 100 mL polytetrafluoroethylene beaker, 5 mL of dilute nitric acid is added, and after thorough shaking, hydrofluoric acid is added dropwise until the sample is completely dissolved. The sample is heated on an electric furnace to boil for 2-3 minutes, then removed and cooled. The sample is transferred to a 100 mL polyethylene volumetric flask, diluted with water to the mark, and shaken well. After dry filtration, the sample is ready for testing.

[0037] The above method requires a hydrofluoric acid-resistant system for testing. The test results are shown in Table 3.

[0038] Table 3: Effect of acid-soluble system on sample dissolution ; As shown in Table 3, the analytical results obtained by using the three schemes of nitric acid-hydrofluoric acid-sulfuric acid-tartaric acid, nitric acid-hydrofluoric acid-hydrofluoric acid resistant system, and acid-hydrofluoric acid-silicon standard solution of the present invention for sample pretreatment are consistent. The nitric acid-hydrofluoric acid-silicon standard solution scheme does not require increasing the fuming time, does not require adding tartaric acid to increase the burden on the injection system, and does not require replacing the expensive hydrofluoric acid resistant injection system, making it more convenient and faster.

[0039] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

[0040] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this invention.

Claims

1. A method for determining the niobium content in a manganese-silicon alloy, characterized in that, Includes the following steps: Step S1: Crush the manganese silicon alloy sample to be tested to a particle size of less than 0.125 mm to obtain the crushed sample; Step S2: Place the pulverized sample in a 100 mL polytetrafluoroethylene beaker, add 1-5 mL of dilute nitric acid, shake well, then add 1-5 mL of hydrofluoric acid until the sample is completely dissolved. Add 3-5 mL of silicon standard solution and heat on a heating device to boil for 2-3 minutes. Remove and cool, then transfer to a 100 mL polyethylene volumetric flask, dilute with water to the mark, shake well, filter dry, and then test. Step S3: Prepare the working curve; Step S4: Adjust the inductively coupled plasma atomic emission spectrometer to the optimal working conditions, measure the intensity of the spectral lines of the analyte using the inductively coupled plasma atomic emission spectrometer, plot the calibration curve with the concentration of the analyte as the abscissa and the spectral line intensity as the ordinate, and determine the niobium content in the sample.

2. The method for determining the niobium content in a manganese-silicon alloy as described in claim 1, characterized in that, In step S2, the amount of sample is 0.10–0.25 g, and the concentration of the silicon standard solution is 2 mg / mL.

3. The method for determining the niobium content in a manganese-silicon alloy as described in claim 2, characterized in that, In step S2, 5 mL of dilute nitric acid, 2 mL of hydrofluoric acid, and 5 mL of silicon standard solution are added.

4. The method for determining the niobium content in a manganese-silicon alloy as described in claim 1, characterized in that, Step S3 specifically involves: weighing 6 portions of high-purity iron and placing them in 6 100mL tetrafluoroethylene beakers, wetting them with water, adding 5mL of dilute nitric acid, heating at 150°C to remove the yellow fumes, then adding 0.1mL of hydrofluoric acid, shaking thoroughly until the solution dissolves, removing and cooling, adding 5mL of silicon standard solution, transferring to a 100mL volumetric flask, then adding different volumes of standard stock solution or standard working solution, making up to volume, and shaking well.

5. The method for determining the niobium content in a manganese-silicon alloy as described in claim 4, characterized in that, In step S3, the sample weight of high-purity iron is 0.04 g to 0.1 g, and the content gradient of niobium standard solution is 0% to 0.5%.

6. The method for determining the niobium content in a manganese-silicon alloy as described in claim 2 or 3, characterized in that, In step S4, the optimal operating conditions for the inductively coupled plasma atomic emission spectrometer are: power 1150 kW, atomizer pressure 26 psi, pump speed 100 rpm, cleaning time 20 s, and integration time 5–20 s.

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